The present invention relates to a centrifugal pump.
Centrifugal pumps comprise a gap between the rotating impeller and the stationary pump part surrounding the impeller. Gap seals are provided, in order to reduce leakage losses from the impeller pressure side to the impeller suction side, which occur at the gap.
Such gap seals are known from U.S. Patent Application Publication Nos. 2006/0147328 A1 and 2007/0160467 A1. The gap seals described there are attached on a stationary pump part which separates the impeller pressure side from the impeller suction side. Typically, despite the gap seal, there exists a gap between the stationary pump part and the impeller which rotates relative thereto. The width of this gap may be designed such that no significant leakage loss may occur, but then there exists the danger of friction between the impeller and the gap seal, which may lead to a wear of the participating friction partner, as well as particularly unfavorably to a blocked pump. Accordingly, with the known centrifugal pumps, a dilemma exists, with regard to a narrow gap causing a minimal leakage, of having to accept a comparatively large wear and a blockage of the pump, or on the other hand with regard to a larger gap, although having a lower wear, of having to accept a relatively large leakage loss.
Against this background, it is an objective of the present invention to provide a centrifugal pump with a gap seal, which should have good wear characteristics with an as low as possible leakage from the impeller pressure side to the impeller suction side.